https://doi.org/10.1140/epjc/s10052-016-4212-8
Regular Article - Theoretical Physics
Two-photon decays of 
from lattice QCD
1
School of Physics, Peking University, Beijing, 100871, China
2
Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
3
School of Science, Xi’an Technological University, Xi’an, 710032, China
4
School of Physics and Center for High Energy Physics, Peking University, Beijing, 100871, China
5
Collaborative Innovation Center of Quantum Matter, Beijing, 100871, China
6
School of Physics, Nankai University, Tianjin, 300071, China
7
Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, 100190, China
8
Department of Physics, Zhejiang University, Hangzhou, 311027, China
* e-mail: liuchuan@pku.edu.cn
Received:
12
May
2016
Accepted:
14
June
2016
Published online:
29
June
2016
We present an exploratory lattice study for the two-photon decay of using 
twisted mass lattice QCD gauge configurations generated by the European Twisted Mass Collaboration. Two different lattice spacings of 
fm and 
fm are used in the study, both of which are of physical size of 2 fm. The decay widths are found to be 1.025(5) KeV for the coarser lattice and 1.062(5) KeV for the finer lattice, respectively, where the errors are purely statistical. A naive extrapolation toward the continuum limit yields 
KeV, which is smaller than the previous quenched result and most of the current experimental results. Possible reasons are discussed.
© The Author(s), 2016
